US2400108A - Wide range flow meter - Google Patents

Description

May 14, 1946.

S. ELOWSON WIDE RANGE FLOW METER File'd Sepf. 4, 1942 a MJ .M F w :inventor fen Elan/san (3mi /fwyd ttqmeg l Patented May 14, 1946 wins RANGE FLow METER l Sten Elowson.` Brooklyn, N. Y.. signor to Pittsburgh Equitable Meter Company, Pittsburgh, Pa., a corporation of Pennsylvania Application september 4, 1942. serial manso-1 12 onine.l (cl. 7a4-20s) This invention relates to apparatus for measuring the rate of flow of fluids.

It is an object o! this invention to provide va ilow meter for measuring a relatively of ilows.

Another object is'the provision of aflowmeterQ of simple and compact construction and oi relatively low manufacturing cost which will accurately measure a relatively wide range of flows. Another obiect is the provision of a now meter calibrated for measuring a relatively'wide range of i'iows wherein the calibration of both low rates of ilowand highy rates of ilow are spaced so as to be easily readable. 1

In accordance with the present invention I provide a flow measuring apparatus having an'area type ilow measuring apparatusfor measuring relatively high rates of flow and an area type flow measuring apparatusfor measuring relatively low rates .of flow, the two measuring apparatus being connected so that Iwhen the flow to be measured `is greater than the capacity of the low rates of Wide range' mio s pipeline, or the mung and tubular casing may be formed as a single piece. A cap member Il is threaded into the top opening I3 of the ntting 3 and a flange I 4with a gasket I3 forms a iluid tight fit therewith.

Sleeve 3 is machined to provide a shoulder I3 upon which is seated a bushing I3 held in iluid tight relation thereto in any suitable manner, as

by solder lor the like. Bushing I3 is machined to provide a reduced centering sleeve portion 2i and a shoulder 22 which receives thereon a tube 23 with a tight tit extending through the exterior casing I and having at'the top a cap or cover 24 with a rabbeted edge portion 23 received within the tube 2 3. Cover 24 is also. bored to provide a seating recess 21 for the end of a tube now measuring apparatus, the measurement will be made by the apparatus for measuring high rates of flow, a common indicator preferably being employed. I preferto embody my invention in a single exterior casing employing a single indicating scale and other parts embodying common or dual functions.

The invention vwill be described in greater detail in connection with the accompanying'drawing showing a preferred embodiment of the `iii- I vention by way of example, and wherein:

Figure 1 is a vertical sectional view of a ferred embodiment of the invention,

AFigure 2 is a vertical sectional view on an en,- larged scaleofa Dart ofthe measuring apparatus,

Figure 3 isa vertical sectional view on an enlarged scale of a detail, and

Figure 4 is a side view of a modiilcation shown on a reduced scale. t

Referring to `the drawing.` there is4 shown a tubular casing iwhich may be in the form of a length of pipe or tube screw threadedatthe botrra' - tom 2 and connected to a reducing sleeve-or iltting 3 whichis screw threaded at the inlet opening 4 so that it may be connected into a suitable pipe line. At the upper portion l of tube I, which is screw threaded, a 'r-iltting 3 is secured having lateral openings 1 and 3, the opening 3 being closed by a'suitabie pipe plug 3. .If desired, a fitby screws 43 and'providing openings 43 for esting having only one lateral opening may be employed, this iltting having a suitable screw threaded opening whereby'it may be connected. ss`

23 which is screw threaded at 23 into a screw threaded central bore 3| in cover Ii and by suitable manual rotating of tube 23 to cause it i to bear against cap 24,'the tube 23 is heldin place on shoulder 22 with a substantially fluid tight flt.

Tube 23 has an oriilce or slot 33 formed-therein which preferably is parabolic'in shape and may be formed conveniently by a suitable rotary cutting tool cutting away a portion of thetube on a plane at an angle tothe axis of the tube. Although I prefer to employ two diametrically opposite slots 33, only one such slot appears in the drawing. Within tube 23 is located an elongated piston 33 having a middle'reduced or relieved portion and flanges 33 and 31 at its ends whichv 4 provide a lclosey working `ilt with the bore of tube 23 on the order of vseveral thousandths of an inch clearance on the diameter. Piston 33 at its bottom h'as acushioning gasket 33 of soft rubber or similar material held in place -between the bottom of flange 31 and gland 33 by screws 4I. Gland 33 has a central hole 42 therein which aligns with a tapered bore 43 in piston 33. Bore 43 tapers from thesmallest diameter-at the bottom to the largest diameter at the top, the taper `preferably beingonthe order of about 45 minutes.

A piston 43 is located in bore 43 and in its lowermost position restsy on a flange v4l provided by gland 33. Piston 43 has about the same per cent taper on its outside diameter as bore 43 and in its lowermost position provides a'clearance with bore 43 on the order of a few thousandals or an inch. At the tcp of piston as is located a cover 41 held on an internal shoulder cape of iluid and a centralropening 33 throughv which extends a rod 3i secured to the piston 45 in any suitable manner, as by a pressed llt, The

which seats thereon and is held in place by a clamping ring 56 and cap screws 5l. Member 55 has a tube 58 extending therefrom and held therein by a ring or' solder or by any other suitable means, the tube being cut away at 59 to provide a sight opening. A cap il@ is suitably sep cured tothe top of tube be, as by screw threads.

A tube Si of glass or other transparent material extends through a bore 62 in member 55 and is held in place therein by a packing G3 or the like engaging the sides of the'tube and pressed into place by a threaded gland or bushing 6ft. Rod or stem 5l extends through tube 2li into glass tube 6l and has a head 65 which' ycooperates with graduations on the tube 58 to indicate rate of flow.-

If desired, a pressure gauge 66 may be secured to the top, this gauge being threaded into a hanged bushing 67 secured by suitable gaskets E58 between the top of cap and the end or glass tube t l.

The operation of the apparatus now will be described. Liquid enters the inlet opening ci, passes through opening 32 and exerts e. pressure against piston The fluid tends to escape Ythrough the minimum clearance space between bore i3 and piston 35, and passes upward through bore Il@ and openings 5t into tube 23 and thence through opening 33 into casing i and out the exit bore l. However, when the rate of iow is greater than can escapethrough this minimum clearance, the piston tb is lifted, thus increasing the clearance between the piston l5 and tapered bore 43 until a point of balance is reached between the elevation of the piston and rate i' :iiow through the clearance. By Calibrating tube 53 in `units ci rate oi how the indicator head @d will show the rate of iiow. Hstons l5 and 355 are so designed that a greater rate of ow ls required to hold piston d in its uppermost position than is required to commence movement of piston 2lb. Thus, there is a slight overlap, and by suitable selection of weights of pistons fl and '15 this overlap may be made as small as practicable and prefton 4B and tapered bore d3, the piston li will be raised to the top of tube d5 into abutment with cover il and will be held in this position, and thereupon piston. 35 will be raised to expose the lower portion ci' slot 33 and allow escape of i'luid therethrough into surrounding casing E. At this flow the upper ange 35i of piston i5 closes ofi the upper end of slot 33 so that now all uld escapes from the lower end of slot 38 under anue 31. Thus,` a balance between the elevation of piston 35 and the area of opening 33 under piston 35 is maintained, and at the position of maximum flow through bore d3 the piston til assumes a fixed position and moves together with piston atto further raise rod El. However, from this point the unit oi calibration on tube 8l changes. Thus, piston 45 may indicate now in units oi cubic feet units of ten cubic feet per minute. Assuming th'e maximum ow through bore 43 to be fteen cubic feet per minute and the maximum iiow allowed by piston 35 through slot 33 to be 250 cubic feet per minute, and assuming the range of movement of piston l5 in bore B3 to be equal to the range of movement of piston 35 in tube 253, then the lower half of the scale on tube 58 will indicate a, iiow up to fteen cubic feet per minute and the top half of the scale will indicate a flow from fifteen cubic feet per minute to two hundred nity cubic feet per minute. Thus, in one instrument is combined a i'low meter for measurihar a wide range of flows and the spacing of the calibrations at the low rates is such as can be easily and accurately read.

In the modification shown in Figure 4, the tube 23 has a narrow slot 'lll at its lower end merging with a tapered slot 'll which' in turn merges with the parabolic opening l2. This construction may be employed to eliminate the diiliculties of machining of the edge of the parabolic slot where it tapers out to a feather edge.

While I have shown the preferred embodiment of the invention a piston movable in a tube with a parabolic slot in th'e tube to measure the high rates of flow, any other suitable area type of measuring device or mechanism may be employed for this purpose. Also, in place 0f a piston movable in a tapered bore for measuring low raus 0f iiow, I may employ any other suitable area type of measuring device or mechanism.

What I claim as my invention and desire to secure by United States Letters Patent is:

l. In a flow meter, a tube having a uniform bore and a parabolic slot in the wall thereof, an elongated piston located in said tube and 0bstructing said bore, said piston having a tapered. bore therein, a second piston located in said tapered bore and obstructing flow through said tapered bore, means providing an escape passage for fluid that passes said second piston into said tube, and means limiting movement of said second piston in said tapered bore.

2. In a flow meter, a tube having a uniform bore and an elongated parabolic slot in the wall thereof, an elongated piston located in seid tube and obstructing said bore, the upper end of said piston lying below the top of said slot, said piston having a tapered bore therein, a second piston locad in. said tapered bore and obstructing rlow through said tapered bore, means providing an escape passage for iiuid that passes saidvsecond piston into said tube, and means limiting movement of said second piston in said tapered bore,

and an indicator operated by the position of said second piston.

3- In a now meter, a casing having an inlet and outlet, a tube in said casing having a slot, a movable member in said tube adapted to obstruct ilow therethrough and providing a relatively large variable iiow therethrough into said slot dependent on the position of said member,

said member in its lowermost position closing the lower endof said slotI `and uncovering the upper end, a second member in said tube adapd to obstruct flow therethrough and providing. a relatively small iiow therethrough dependent othe position of said second member, mea-ns providing a passage for said small ilow to said tub-e whereby it flows through the upper end of the tube through said slot into the outlet, said means being restricted by movement of said second member to its maximum .flow position whereby said first movable member is moved by 'the flow 4. In a flow meter, a casing having an inlet and an outlet, a tube located in said casing having an opening in the wall thereof, a'. piston located in said tube adapted to obstruct ilow therethrough, means providing a stop for the piston to position the lower end thereof over said opening leaving the upper end of the opening unobstructed, there being a bore in said piston, a second piston in said bore, means limiting downward movement of said second piston, a cover for said bore providing for ilow of 4iluid from the upper end of said bore into said tube, and indicating means attached to said second piston.

5, In a now meter, a casing having an inlet and an outlet, a rst cover closing the upper end of said casing, a ilrst tube located in. said casing having an opening in the Wall thereof, a second cover having man opening therein for said tube, a second tube screw threaded into said rst cover and engaging said second cover about said second opening, a sight glass secured to said ilrst cover in alignment with said second tube, vand closed at its end, a piston located in said first tube, means providing a stop for the piston to position the lower end thereof over said first-mentioned opening leaving the upper end of the rst mentioned opening unobstructed, there being a bore in said piston, a second piston in said bore, means limiting downward movement of said second piston, a

` cover for said bore providing for iiow oi' fluid from the upper end of said bore into said ilrst tube, and indicating means secured to said second piston extending through said second tube into said sight glass. y

6. In a fluid 'ilow meter, a casing having an inlet and fluid escape means, a member in said casing closing said escape means from the inlet when in one position, said member having a ilow passage therethrough, escape means in said cas-v ing for fluid flowing through said passage, movable means in said passage providing a variable ilow through said passage relative to the position oi' said movable means in the passagasaid member being movable by ilow oi' fluid to close o!! the second mentioned escape means and uncover said first mentioned escape means, and an indicator associated with said movable means.

"1. In a iluld flow meter, a casing having an inlet and fluid escape opening, a member in said casing closing said escape opening from the inlet when in one position, said escape opening extending beyond said member, said member havning a flow passage therethrough communicating with the extended portion ot the escape opening, movable means in said passage providing a variable flow through said passage relative to the position of said movable means in the passage, said member being movable by now of nuid to close oiI the extended portion of the escape opening and uncover said rst mentioned escape open.. lng, and an indicator associated with said movable means.

8. A wide range ilow meter comprising a casi casing only in response to rates of fluid iiow` chiefly higher than those which displace said first member, said second member being opposed to the iiow of iluid at said inlet and movable in the direction of iiuid flow, and an indicator operably connected to said members for actuation through one range when said first member is displaced-and for actuation through a further higher range correlated with said one range Awlriensaid second member is displaced.

9. A wide range iiow meter comprising a casing having inlet and outlet openings, means in said casing delning a passage between said open.- ings, a compound piston assembly movable within said casing and directly opposed to fluid ilow through said inlet opening, said piston assembly comprising a first piston element independently movable in the direction` of iluld now in response only tov lrelatively low rates of iluid flow, and a second piston element movable iny the direction of iluid ilow in response only tolrelatively higher assembly for actuation by movement of said first piston element through one range and for actuation by movement of said second piston element through a higher range correlated with saidone range.

Al0. The wide range ilow meter denned in claim 9, said indicator comprising a movable indicator element operably connected to said first piston element, and means connectingsald piston elementsV for movement together only when said rst piston element reaches a position corresponding to the upper limit of said one range.

l1. In a fluid ilow meter having an inlet and an outlet, a plurality of closure members for the inlet of relatively different specific gravities, each directly opposing the inlet pressure and individually movable from normal position in response to relatively Adifferent rate ranges of liiuid flow, and a common dow rate indicating element operatively connected with and actuated by each of said closure members.

12. In a iluid tlow meter having an inlet and an outlet. a. plurality of closure members for the inlet constructed and arranged in permanently nested relation, said members being of relatively dlllerent specific -gravitles and individually movable from normal position in response to relatively dll'rerent rate ranges of fluid flow. and ilow rate indicating means operatively connected with and actuated by each of said members.

STEIN EUOWBON.

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